Compass deviation corrector



Patented Apr. 2, 1935 UNITED STATES ,PATENT olii-Ice 1 Claim.

as are used in aircraft'o'r small water-craft.

The principal objectY of the invention is to provide a deviation corrector which'may be used for y correcting ordinary semici'rcular deviations with substantial accuracy by persons unfamiliar with magnetism or magnets vorth'eir effect upon the compass.

Another object is to provide a simplied mechanism for obtaining the results hereinabove described, which will require only the simplest of i verbal or written instructions for operation, and

which will further be completely housed against accidental disturbance of adjusted parts or loss of parts, prior adjustment. Y

It is common Vto theart to position aircraft or water-craft in a series of known magnetic headings through employment of a swinging base or table. four cardinal magnetic headings may be readily effected through employment of Vthe-hereinafter described mechanism.

With the foregoing and other objects lin View, which will appear as the description proceeds, the invention consists of improvements embodied in a semicircular deviation corrector asl hereinafter more fully illustrated and described in the accompanying kdrawing and more particularly Y pointed out in the appended claim.

Referring to the drawing', in which numerals of like character designate similar parts through the several views:

Fig. lis a diagrammatical sideview of a compass card, and

Fig. la is a corresponding View of the attached magnets showing relative positioning of the com'- pass deviation corrector element with reference to the north heading;

Fig. 2`is a diagrammatical side View of the card,` and Fig. 2a is a corresponding view of the corrector elements;

Fig. 3 iS a diagrammatical plan view of the above showing relative positionings of the compass card and attached magnets andthe com pass deviation corrector element;

Fig. 4 is a diagrammatical plan and end view of a modied form of compensating magnet and container;

Fig. 4a is an end View of the parts of Fig. 4.

Fig. 5 is a cross-sectional side view ofV an ordi- Compensation of the compass for they nary aircraft compass embodying ments of my invention; l

Fig-6 is a cross-sectional plan view of the above compass through the compass deviation corrector element taken on line 6 6, Fig. 5; and

Fig. 7 is a partial side view of the 'compass deviation corrector element housing.

rThe principal'parts of my invention consist of the small V shaped compensating` magnets I secured in containers 2 and 3. The containers 2 and 3 areretained in fixed relationship to each other by means of the shafts# and 5. The foregoing, forming the basic parts of the corrector element proper, are placed immediately beneath the compass card 6, to which are permanently securedfthe compass card magnets 1. In Figs. liand 2 the axis O-O passes vertically through the mid-points of longitudinal axes X-X and Y-Yv of the shafts 4 andr 5 and through the centroid of the plane"y of symmetry of the 'compass card 6. Axis X-X is shown immediately beneath 'and parallel to a center linepassed the improven ofi" through the north and Southheadingsof'the compass card ii and is further shown equidistant from and parallel to the longitudinal axes Z-Zl been so positioned 'that planes *dividing each magnet into Vtwo equal V shaped parts will be parallel to a plane passed through the axes Z--Z ofthe compass card magnets 1. Equally desirableV results `may be obtained if theN foregoing parts forming the corrector element,- are placed immediately above the compasscard 6,theQposition of all parts discussed above remaining the same with reference to the vertical axis O-O.

Fig. 4 shows a modification of4 compensating magnet l and containers' 2 and-3. Two compensating magnets 8 are secured parallel tov andfL equidistant from shaft 4 in the container f9'. `It

will be noted that rthe vpolarity arrangement of n Fig. 3 has been retained by placement of thenorth pole of the right-hand magnet and the south pole of the left-hand magnet at the outer extremity of container 9.

The operation of my invention is as follows: Providing the strengths of the compensating magnets I shown in Figs. 1 through 3 are of equal magnitude, there will theoretically be exerted n0 It will be still further noted, in Figs'l,

influence upon the magnetic eld in which the card magnets 1 are immersed as long as the planes dividing the compensating magnets I into two equal V-shaped parts are maintained parallel to the plane through the center lines of the card magnets `7. The above described positioning of the compensating magnets l is called the neutral position.

When the containers 2 shown in Fig. 1 through 3 are rotated in either direction from the neutral position referred to @boi/e through a certain angle, the standing elds of these magnets rotate with Vthem through the same angle and exercise` a deflecting force upon the magnetic eld in which magnets are immersed, which deflects this latter field in such a direction and. through such an angle as will eiect compensation on the north heading.

When the containers 3 shown in Fig. 1 through 3 are rotated in either direction from the neutral-pesition referred to above through a certain angle, the standing fields, ei these magnets rotate with them through the same angle and exerciseandeflecting force upon the magnetic field vwhich-n i agnets 'l are immersed which deiects this latter field in such a direction and through such an angle as will effect compensation on the West heading. s

Figs. 5 and 6 show the application of my invention to an ordinary compass. Jfid-justment of the containers 2 and 3 is accomplished through depression of the locks l out of their detents Ilagainst the tension of the springs i2 and rotation 4of the pinions i3 rigidly lattached to the locks. I Q. by means, of the shafts M. The above rotations resuitlin corresponding rotation of the gear t5; rigidi-y, attached to one of the containers 3*! or correspondingl rotation of the gear I6 rigidly attached to one of the containers 2. As has been previously stated containers 2 are held in xed relationship to each other by means of the shaft 4,', and containers 3, are held in similar relationship to each other by meansv of the shaft 5. The; balanceof the parts shown in Fig.. 5 oomprise, Conventional elements of anordinary compassand special reference is made herein only to cover glass i8 and lubber line |-9 of Fig. 5.

Eig, 7 shows that portionof the exterior of the deviation corrector housing l1, which lies immediately beneath the cover glass I3. Itwill be noted4 that the right-hand. lock id` has been marked; N on; the leftV andv S on the righthand portion of the lock face. It will also be noted that theV left-hand-lock thas been marked E on the-left and W on the right-hand portionA of the lockface and that pin holes 2G have beenincorporated in the faces 0f both locks to` permitr rotation of the locks by means of an ordinary, pin-faced key. The proles of the detents ll are also clearly shown in Fig. 7.

As has been stated above, it will be necessary to-furnish the person seeking tor compensate the compass ot an aircraft or smallwatercraft equipped with the above-described deva-tion'cor- Y nectonwithsimple verbal or written instructions upon the following; Let it be assumed that thevlubber line` t9 of the compass has been placed in proper fore-and-aft relationship to the craft and that' the crafthas been put onto a north course by means of a swing base. Let it be further assumed that the compass card 6' has been found to indicate a reading of 3D degrees. It is obvious that the compass card 6' must be rotated 30 degrees in a clockwise direction if the north cardinal of the card is to be made to coincide with the lubber line I9, as Viewed through the cover glass I8. Clockwise rotation of the compass card 5' may be accomplished by counterclockwise movement of the right-hand lock I il, the latter movement directly controlling the degree of compass card compensation desired. If the craft is then swung onto a south course, it

will be found that clockwise movement of the right-hand` lock t0 will produce clockwise compensation of the compass card 6', and counterclockwise movement of the same lock, counterclockwise compensation of the card. It may be discovered that compensation of the south cardinal has adversely affected previous compensation of the north cardinal, in which case it will be necessary to adopt that compensation compromise which will result in minimum combined de.- viation of the north and south cardinals from the lubber line I9. If the craft is further swung ontoA an east course, it will be found that counterclockwise movement of the left-hand lock IE! will produce clockwise compensation of the compass card 5', and vice versa. Finally, if the craft is. swung onto a west course, it will be fomid that clockwise movement of the left-hand lock LB will produce clockwise'compensation of the compass card and vice Versa. Also, it may be nec,- essary to adopt compensation compromise between the east and west cardinals with. reference to minimizing combined deviation from the lubber line I9.

This invention is provided for the purpose of Vcorrecting deviations known as semicircular deviations of the compass-as expressed by the coefficients B and C in the theory of compass adjustment. 1t is not designed to take care of such extraordinary or unusual deviations as correction of quadrantal deviations arising from masses of soft iron in proximity to the compass. The corrections providedV by this, invention Will, however, except in most unusual cases, be amply sufiicient. for small Compasses such as are used in aircraft or small water-craft.

What I claim as. new and desire to secure by.

Letters Patent, is:

A compass deviation corrector comprising, a housing, two sets of magnets carried by said housing.each set Vbeing xed at right angles tothe other and to a vertical axis of reference, each set of said magnets including diametrically oppositely disposed magnets having a common axis of sym.- metry and being arranged so that their adjacent ends are dissimilar in polarity, the oppositely dis.- posed magnets of each set of magnets being equidistant from said vertical axis, their axes of sym,- metry intersecting said vertical axis, means for supporting the magnets of each set of magnets in relatively xed relationship, and further means for individually adjusting said supporting means to adjust each set of magnets as a unit about its axis of` symmetry to a desired setting.

VICTOR E. SHOWALTER. 

